B2 cell division Flashcards
What is a gene?
The basic unit of genetic material inherited from our parents. A gene is a section of DNA which controls part of a cell’s chemistry - particularly protein production.
What is a Chromosome?
Genetic structures that usually occur in functional pairs in the nucleus of cells (except in gametes and bacteria).
How much chromosomes do human usually have in one cell nucleus
Humans have 46 chromosomes arranged in 23 pairs.
What are genes and alleles?
A gene is a short length of DNA found on a chromosome that codes for a particular characteristic or protein.
Alleles are different forms of the same gene.
What are the 4 bases in DNA?
A = adenine
T = thymine
C = cytosine
G = guanine
What is DNA?
Deoxyribonucleic acid. The material inside the nucleus of cells, carrying the genetic information of a living being.
When do cells need to divide?
an organism grows
an organism becomes damaged and needs to produce new cells
What is the cell cycle?
The series of stages that a cell goes through as it is growing and dividing.
What is Mitosis?
A type of cell division which produces daughter cells identical to the parent
What are the 3 stages of the cell cycle?
Stage 1:
chromosomes replicated and all sub-cellular structures such as
mitochondria and ribosomes reproduced
stage 2: (mitosis)
nucleus divides to form two identical daughter nuclei
stage 3:
cytoplasm and cell membranes divide to make two
independent cells
What are stem cells?
A cell found in foetuses, embryos and some adult tissues that can give rise to a wide range of other cells.They are undifferentiated.
What is differentiation?
When an unspecialised cell becomes a more specialised cell type
Why is cell division by mitosis important in the Human body?
New cells needed for growth and development, and worn out or
damaged cells must be replaced with identical cells.
Mitosis produces cells with same chromosomes and identical genetic
material, which fulfil same function as original cells.
Where does cell division take place in plants?
In the Meristem (region in plant shoots and roots in which cells are dividing, and so are undergoing mitosis.)
How does the differentiation abilities of plants and animals affect their ability to clone?
In plants differentiation can be reversed and mitosis induced.
Conditions can be changed to induce more mitosis.
Cells redifferentiate into different plant tissues needed to form a new
clone plant,
so plants can be cloned relatively easily.
In animals differentiation cannot be reversed (cells differentiate
permanently),
so clones cannot be made easily.
In order to make animal clones, embryos have to be cloned.